9985/3 Refractory cytopenia with multilineage dysplasia

Definitions

Tumours of haematopoietic and lymphoid tissues

ICD-O-3 topography code:

C42 and C77

ICD10:

D46.5

Refractory cytopenia with multilineage dysplasia (RCMD) is a type of myelodysplastic syndrome (MDS) with one or more cytopenias and dysplastic changes in two or more of the myeloid lineages: erythroid, granulocytic, megakaryocytic 1

. There are <1% blasts in the peripheral blood (PB) and <5% in the bone marrow (BM); Auer rods are not present and the monocytes in the PB are less than 1x109/L. The recommended levels for defining cytopenias are haemoglobin <10g/dL, absolute neutrophil count <1.8x109/L and platelet count <100x109/L 2

. However, values in excess of these thresholds are not exclusionary of a diagnosis of MDS if definitive morphologic and/or cytogenetic findings are consistent with a diagnosis, e.g. complex cytogenetic abnormalities. The thresholds for dysplasia are ≥10% in each of the affected cell lines. In assessing dysplasia it is recommended that 200 neutrophils and precursors and 200 erythroid precursors be evaluated in smear and/or trephine imprint preparations. The neutrophil dysplasia may be evaluated in PB or BM smears. At least 30 megakaryocytes should be evaluated for dysplasia in BM smears or sections. In some cases, dysplastic megakaryocytes may be more readily identified in sections than smears. In particular the presence of micro?megakaryocytes should be noted. Cases with multilineage dysplasia and 2−4% blasts in the PB, <5% in the BM, and no Auer rods should be classified as refractory anemia with excess blasts(RAEB)-1; cases with 1% blasts or fewer in the PB and <5% blasts in the BM, and Auer rods should be classified as RAEB-2; cases with 1% blasts in the PB and <5% in the BM and no Auer rods should be classified as myelodysplastic syndrome, unclassifiable (MDS-U). Some cases of RCMD have ≥15% ring sideroblasts 4